// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_TXDB_H
#define BITCOIN_TXDB_H

#include <blockfileinfo.h>
#include <coins.h>
#include <dbwrapper.h>
#include <flatfile.h>
#include <kernel/caches.h>
#include <kernel/cs_main.h>
#include <util/fs.h>
#include <util/result.h>

#include <cstddef>
#include <cstdint>
#include <functional>
#include <memory>
#include <optional>
#include <string>
#include <utility>
#include <vector>

struct BlockHash;
class CBlockFileInfo;
class CBlockIndex;
class COutPoint;

namespace Consensus {
struct Params;
};
namespace util {
class SignalInterrupt;
} // namespace util

//! User-controlled performance and debug options.
struct CoinsViewOptions {
    //! Maximum database write batch size in bytes.
    size_t batch_write_bytes{DEFAULT_DB_CACHE_BATCH};
    //! If non-zero, randomly exit when the database is flushed with (1/ratio)
    //! probability.
    int simulate_crash_ratio = 0;
};

/** CCoinsView backed by the coin database (chainstate/) */
class CCoinsViewDB final : public CCoinsView {
protected:
    DBParams m_db_params;
    CoinsViewOptions m_options;
    std::unique_ptr<CDBWrapper> m_db;

public:
    explicit CCoinsViewDB(DBParams db_params, CoinsViewOptions options);

    bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
    bool HaveCoin(const COutPoint &outpoint) const override;
    BlockHash GetBestBlock() const override;
    std::vector<BlockHash> GetHeadBlocks() const override;
    bool BatchWrite(CoinsViewCacheCursor &cursor,
                    const BlockHash &hashBlock) override;
    CCoinsViewCursor *Cursor() const override;

    //! Whether an unsupported database format is used.
    bool NeedsUpgrade();
    size_t EstimateSize() const override;

    //! Dynamically alter the underlying leveldb cache size.
    void ResizeCache(size_t new_cache_size) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    //! @returns filesystem path to on-disk storage or std::nullopt if in
    //! memory.
    std::optional<fs::path> StoragePath() { return m_db->StoragePath(); }
};

/** Specialization of CCoinsViewCursor to iterate over a CCoinsViewDB */
class CCoinsViewDBCursor : public CCoinsViewCursor {
public:
    ~CCoinsViewDBCursor() = default;

    bool GetKey(COutPoint &key) const override;
    bool GetValue(Coin &coin) const override;
    unsigned int GetValueSize() const override;

    bool Valid() const override;
    void Next() override;

private:
    CCoinsViewDBCursor(CDBIterator *pcursorIn, const BlockHash &hashBlockIn)
        : CCoinsViewCursor(hashBlockIn), pcursor(pcursorIn) {}
    std::unique_ptr<CDBIterator> pcursor;
    std::pair<char, COutPoint> keyTmp;

    friend class CCoinsViewDB;
};

/** Access to the block database (blocks/index/) */
class CBlockTreeDB : public CDBWrapper {
public:
    using CDBWrapper::CDBWrapper;
    bool WriteBatchSync(
        const std::vector<std::pair<int, const CBlockFileInfo *>> &fileInfo,
        int nLastFile, const std::vector<const CBlockIndex *> &blockinfo);
    bool ReadBlockFileInfo(int nFile, CBlockFileInfo &info);
    bool ReadLastBlockFile(int &nFile);
    bool WriteReindexing(bool fReindexing);
    bool IsReindexing() const;
    bool WriteFlag(const std::string &name, bool fValue);
    bool ReadFlag(const std::string &name, bool &fValue);
    bool LoadBlockIndexGuts(
        const Consensus::Params &params,
        std::function<CBlockIndex *(const BlockHash &)> insertBlockIndex,
        const util::SignalInterrupt &interrupt)
        EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
    ;

    //! Attempt to update from an older database format.
    //! Returns whether an error occurred.
    bool Upgrade();
};

[[nodiscard]] util::Result<void>
CheckLegacyTxindex(CBlockTreeDB &block_tree_db);

#endif // BITCOIN_TXDB_H
